At the "Press Start Button" screen after the game initially loads, press Up(2), Down(2), Left, Right, Left, Right, B, A to unlock a "Cheats" option, which includes options like "God mode", in the extras section of the pause menu. If you entered the code correctly, Gabriel will wink. Note: Enabling cheat options will prevent achievements from being earned and the game from being saved.

Game Of Thrones reference

In the greenhouse, just as you defeat Pan's brother, stand in front of Pan's corpse. Directly behind you will be a statue on a plinth, in a sunken part of the terrain. The plinth is in a pool, and behind it is a dead soldier with a diary titled "Company Of Eddard S." The text also mentions "Poor King Robert", as Eddard's Captain.

Achievements

Accomplish the indicated achievement to get the corresponding number of Gamerscore points:

Prince of Darkness (50 points): Complete the game at "Prince of Darkness" difficulty.

Kleidos Champion I (20 points): Complete all the Reminiscences of Sapphire challenges.